<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box {
            width: 200px;
            height: 200px;
            border: 1px solid;
            background-color: blueviolet;
        }

        /* 鼠标悬停在 .box 上方时执行以下CSS */
        .box:hover {
            /* display: none; */
        }

        /* hover A标签，CSS作用于B标签，A和B必须是包含关系 */
        .box:hover h1 {
            color: #fff;
        }
    </style>
</head>

<body>
    <div class="box">
        <h1>你好</h1>
    </div>
</body>

</html>